An obtuse angle is an angle that is more than 90 degrees (a right angle). So Anywhere from 91 degrees to 179 degrees is an obtuse angle. 180 degrees would be a straight line. An acute angle would be anywhere from 1 degree to 89 degrees.
An easy way to remember this is to use your index finger and your thumb. When they are close together you can think of a cute little bug, such as the acute angle. When your fingers make an L then you an think of it being a right angle ( Right being the opposite of left). Lastly you an think of your fingers being longer than a right angle as an obtuse elephant.
This helped me a whole lot when i was in 6th and 7th grade and i hope it helps you too.
